Can’t install Exchange 2010 RTM when Exchange 2007 SP3 exists

I am faced with a very funny issue at a client where I'm migrating from Lotus Domino to Exchange.

As you might know Microsoft didn't release migration tools from Lotus to Exchange 2010 directly so the path was Domino -> Exchange 2007 and then Exchange 2007 -> Exchange 2010.

Since Exchange 2007 SP3 has been released a couple of days ago I've installed it on, what I was planning to be, a temporary server.

I was surprised today that I was not able to install Exchange 2010 and setup.com /PrepareSchema failed with the following error.

Setup encountered a problem while validating the state of Active Directory. The Active Directory schema version (14625) is higher than the Setup’s version (14622). Therefore, PrepareSchema can’t be executed.

I have searched but didn't find anything about this error online, however my best guess is that Exchange 2007 SP3 raised the schema version to 14625 which is higher than the Exchange 2010 RTM schema version 14622. Looks like I'm stuck with Exchange 2007 SP3 untill Exchange 2010 SP1 is out of beta !

Edit July 30, 2010
Looks like this is becoming more popular and has been blogged about here and here

About Antoine Khater

I have been working in IT consultancy and solution integration since 1998 and I consider myself lucky to be, one in a few, making a living out of my passion. I am also member of the famous Experts Exchange (profile here) online community where I try my best to share what I have learned along the road.